midge

Myvatn is a shallow, eutrophic lake in north Iceland. The name means Midge Lake and the area is inundated with them every summer. Luckily, when we visited the midge swarms were of non-biting chironomid species (it’s very handy traveling with an entomologist!).

Besides being beautiful, formed from volcanic action and full of wildfowl, Lake Myvatn is also famous for balls of algae known as lake balls, marimo (Japanese) or kúluskítur (Icelandic). These are spherical colonies of filamentous algae (Aegagropila linnaei) which are thought to form when algae living on the rocks are torn off and are rolled around in the lake currents. Rolling helps to keep the ball clear of debris and mud so the colony stays velvety green.

Tantalizing greenness on the lake bed – could they be algal balls?

Recently, however, lake balls have been vanishing from Lake Myvatn as sediments begin to silt over the the lake floor. They can be seen in aquaria in a few places in Iceland, I hope they will still survive in their famous lake home too.